I'm curious to find out what is the most efficient speed for other Smarties.  I've always been told 50-55mph is the most efficient speed.  However while testing out my new guage (and I have no clue if it actually is acurate) it seems to give me the highest MPG reading at 74-75mpg.  Is this right?  I haven't finished calibrating my device yet... so far its at +65%, and seems to read pretty close to my calculated MPG (it reads around 12MPG @45mph before calibrating, which obviously isn't correct), either way the highest reading regardless of calibration should be the most efficient speed, right? What the actual MPG is, well that's another story.

 

Has anyone tested different speeds, preferably with an accurate gauge (ie... scan guage II) to find out which is the most efficient.  I know miles out/gallons in is the most accurate overall... but that doesn't help with the exact speed for peak efficiency.

 

I'm a science teacher, so I like my data, and repeatability/validity of results.  (and am wishing I had the data logger right now... so many variables especially with no cruise control!)

Tags: MPG, efficiency, instant, kiwi, scanguage

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~On A Side Note~
The Smart delivered a rather frugal 33 mpg city and 41 mpg highway in the 2008 EPA tests. And that's not good enough, says Smart's parents at Mercedes-Benz
http://www.popularmechanics.com/blogs/automotive_news/4270406.html
Would be great for the daily comute, but no good for trips... a 70 mile limit is too limiting for me. (Just not a fan of the all electric... especially not until we have a better power grid that utilizes clean energy... ei, more nuclear.) The Micro Hybrid definitely has more potential.

Brabus007 said:
~On A Side Note~
The Smart delivered a rather frugal 33 mpg city and 41 mpg highway in the 2008 EPA tests. And that's not good enough, says Smart's parents at Mercedes-Benz
http://www.popularmechanics.com/blogs/automotive_news/4270406.html
I have no gauge and I'm no science teacher; but I believe my smart (2009 Brabus Coupe, no aftermarket changes/additions) gets the best mileage at 60 MPH. I know this because a recent two week job required a daily round trip drive of 150 miles. All but 15 miles were highway driving; posted speed limits varied from 45 MPH (construction zone), 55 MPH (in the city), 65 MPH (suburbs) and 70 MPH (between the two cities). The largest part of the trip, roughly 50 miles, was at 70 MPH. Over these ten days I drove those 50 miles at different speeds. Well, 55 MPH was way to slow - fully loaded semis were easily passing me on uphill grades - but 70 MPH was way too shaky for me. Bottom line, at 70 MPH my mileage was a poor 39 MPG, but at 60 MPH,the mileage was a not-too-bad 44.

This may not help you with exact speed for peak efficiency but it has convinced me that my goKar likes to cruise at 60 MPH no matter the speed limit, and we always ignores any angry stares or horns from other cars.
I am by no means a mpg freak and have a "solid" right foot... with the scan gaugeII, I am always hovering around 43mpg (A/C) or 45mpg (with A/C) on highway and ("in theory"... for those highway patrol officers out there...) do go way beyond 80mph... Now in town cruising about at 45-50mph I continuously achieve 50+mpg (no A/C).
I have kept pretty good track of our mileage so far; no scanguage just monitoring overall MPG. On a recent 315 mile trip that was a mix of interstate (70 mph), state highways (55-60 mph) and city (0-45 with numerous stoplights). Overall average 49.25 mpg; I estimate that 75% of the miles were from 55 to 70 mph. Most of our mileage has ranged from 38 mpg low to the 49 as high; most of the time 39-40ish regardless of speed mix. I drive entirely in auto and accelerate carefully. Otherwise no special high mileage techniques.
Driving today, my gerbil didn't seem to like the 50-60mph range. 45mph was giving me some pretty high reading today, 68MPG. Then it seemed to drop to 41ish between 50-60mph. Then rise again around 70-74 to 62MPG (again, I have no clue if my guage is accurate...) My overall for today's trip was 39MPG (which is around what I exect for the type of driving) Good fillups have been in the 38-39MPG range... bad driving tends to get 32-34MPG at the pump.

Need to now pay attention to how close I am to the car in front of me... or no car to slip stream behind. Optimal distance w/out tailgating, to reduce drag?
I have an "ecometer" and when I first plugged it in it would tell me I was getting high 40's to mid 50's but when I would fill my tank and do the math the reality was I was getting my normal mpg in the high 30's range(38-39). Then I fine tuned it by setting the efficiency (engine efficiency setting) down to around 82-83% and then my readings on the Ecometer and my real world readings started to match more closely. I have been contemplating getting a Scanguage II because I would like to have other engine readings available and I am curious whether or not it has a setting for engine efficiency? Are those who's Scanguage II tell them they are getting 50+ mpg getting that same reading when calculating mpg at the pump after a fill up?
It makes sense that it rise again at 70+ as the MIVEC variable valve thingly kicks in to bring up the efficiency at higher rpm.

jaybudder said:
Driving today, my gerbil didn't seem to like the 50-60mph range. 45mph was giving me some pretty high reading today, 68MPG. Then it seemed to drop to 41ish between 50-60mph. Then rise again around 70-74 to 62MPG (again, I have no clue if my guage is accurate...) My overall for today's trip was 39MPG (which is around what I exect for the type of driving) Good fillups have been in the 38-39MPG range... bad driving tends to get 32-34MPG at the pump.

Need to now pay attention to how close I am to the car in front of me... or no car to slip stream behind. Optimal distance w/out tailgating, to reduce drag?
We drove from Near Philly up to Waterville Valley, New Hampshire, and got over 55, and considered that very GOOD. We get about 40 around town, and only fill up once a month.
Love the car, so fun to drive. Ours is a convertible and when ever we can we put our top down.
Especially in the summer.
Betty Ann Byrns
I have a different gauge than the scanguageII or the ecometer (mine does all the other stuff and more... but the company stinks). I have my efficiency set to 70% right now, but still need to do more tests before I totally trust it. Had been running at 65% but that seemed to low. Unfortunatily mine only counts a trip for engine on to engine off, so I'm not getting a reading for what a tank of gas is getting for mpg. (it shows me averages of my lastest trips, but not an overall) I have not done a test of fill up, drive, fill up to compare the two, yet... I need an excuse for a road trip.

I hear with the scanguage you have to enter your gas amount or something each time you fill up then it somehow recalculates... Don't know if you do this everytime, or just until it is fully calibrated. Even if your efficiency isn't calibrated properly yet, if the reading goes up, the mpg is going up, too, right? Have you tested specific speeds... what consistant speed gets you the highest reading? What do you get @55, 70, 78? (I know it will vary on conditions... just curious how yours reads)

How does the ecometer work? Does it calculate the average for the fill up, or just individual trips like mine? Wonder if efficience is the same on both meters?

Seumas said:
I have an "ecometer" and when I first plugged it in it would tell me I was getting high 40's to mid 50's but when I would fill my tank and do the math the reality was I was getting my normal mpg in the high 30's range(38-39). Then I fine tuned it by setting the efficiency (engine efficiency setting) down to around 82-83% and then my readings on the Ecometer and my real world readings started to match more closely. I have been contemplating getting a Scanguage II because I would like to have other engine readings available and I am curious whether or not it has a setting for engine efficiency? Are those who's Scanguage II tell them they are getting 50+ mpg getting that same reading when calculating mpg at the pump after a fill up?
What is this MIVEC thing you speak of? How does it work? Is good or bad for the engine to be in that mode?

Tori said:
It makes sense that it rise again at 70+ as the MIVEC variable valve thingly kicks in to bring up the efficiency at higher rpm
I have 950 miles on my Smart. So far I have averaged about 35mgp. Not bad for the type of driving I do. About 1/2 at 70mph and the other in the city. Its a lot better then what I used to get with my old Chev Metro. For the same drive, I only got about 28mpg

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